SCP: Update NAT support to libslirp 4.8.0

Rip-n-replace the older slirp implementation with libslirp 4.8.0, which
includes a minimal glib stub implementation. No SIMH-specific
modifications made to libslirp so that future updates are easier to
apply.

Other changes:

- ETHER: Move UNIT service activation earlier

  Move the UNIT service activation to after the packet is placed in the
  Ethernet interface's read queue, vs where the "wakeup" was in the
  reader thread's loop. If AIO ism't pending for the UNIT, the UNIT gets
  scheduled via sim_activate_abs(). Uses sim_unit_aio_pending()

  Solves a mystery stall when trying to FTP NetBSD's pkgsrc archive.

- SCP: sim_unit_aio_pending()

  Add a predicate function that returns TRUE if the UNIT has pending
  asynchronous I/O work to be done. Used in _eth_callback (sim_ether.c)
  to schedule the UNIT's service function if necessary (no need to
  schedule the service function if it's already going to be called.)
  Does not depend on being in the main SIM thread.

- SCP: sim_misc_debug()

  sim_misc_debug() enables debug output from non-devices, e.g., libslirp's
  debug output, for consistent output formatting.

- CONSOLE: On Win32, don't repeatedly call GetConsoleMode() each time
  sim_console_write() is called. Use an output function pointer to
  invoke WriteConsoleA (console output) or WriteFile (output is not
  a console).

- CMake

  - Clang updates for Windows (CLANG64 environment from MinGW64).

  - MinGW64 environment: Place binaries under BIN/$MSYSTEM, keep
    BIN/Win32/_config_ reserved for MS-compiled simulators.

- Fix printf() formats for MinGW64-related compiles.

- makefile

  - SDL2_ttf: Only generate info messages iff BESM6 is going to be
    compiled. Do no generate SDL TTF or missing font file warnings when
    compiling pdp11 or any other simulator.

  - SYS_LDFLAGS: System (non-feature) libraries that should be appended to
    the compiler's command line, such as -lm, -lpthread, -lrt and -ldl.

  - Detect features required by the libslirp.a library by compiling a
    small configuration program. (NOTE: This technique can be expanded
    to detect other simulator-required or SIMH-required features.)

  - Use a library, BIN/libslirp.dir/libslirp.a, to provide libslirp
    support rather than compiling libslirp/src/*.c for each simulator that
    uses networking support.

  - Per-simulator "_LDFLAGS" so that only only the libraries needed are
    provided to the compiler. Only added to simulators that use video and
    networking. No real point in dragging SDL2_ttf into simulators other
    than BESM6, for example.

.github/workflows/build.yml

@@ -40,28 +40,33 @@ jobs:
           - scelbi 3b2 i701 i704 i7010 i7070 i7080 i7090 sigma uc15 i650 sel32 intel-mds ibm1130
     steps:
       - uses: actions/checkout@v4
-      ## Workaround for remnant symlinks in /usr/local pointing back to
-      ## macOS frameworks.
-      ##
-      ## Future: Will have to keep an eye on SDL_ttf's Python dependency
-      ## so that the correct/appropriate Python version is removed.
-      - name: Remnant symlink cleanup (macOS)
+
+      ## Nuke homebrew and start with a clean instance:
+      - name: Reinstall HomeBrew (macOS)
         if: ${{runner.os == 'macOS'}}
         run: |
-          brew unlink python@3 || true
-          brew uninstall --ignore-dependencies python@3 || true
-          brew unlink [email protected] || true
-          brew uninstall --ignore-dependencies [email protected] || true
-          for f in $(find /usr/local/bin -type l -print); do \
-            (readlink $f | grep -q -s "/Library") && echo Removing "$f" && rm -f "$f"; \
-          done || exit 0
+          /usr/bin/sudo /bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/uninstall.sh)"
+          [ -d /opt/homebrew ] && ( sudo rm -rf /opt/homebrew/* || true )
+          [ -d /usr/local ]    && ( sudo rm -rf /usr/local/*    || true )
+          /bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install.sh)"
+
       ## Install our regular dependencies.
       - name: Install dependencies (macOS)
         if: ${{runner.os == 'macOS'}}
-        run: sh -ex .travis/deps.sh osx
+        run: |
+          sh -ex .travis/deps.sh osx
+
       - name: Install dependencies (Linux)
         if: ${{runner.os == 'Linux'}}
         run: sh -ex .travis/deps.sh linux
+
+      - name: libslirp module
+        run: |
+          git submodule sync
+          git submodule set-url -- libslirp https://gitlab.freedesktop.org/bscottmichel/libslirp-minimal.git
+          git submodule set-branch --branch incr-minimal libslirp
+          git submodule update --init --recursive --remote
+
       - name: makefile build
         env:
           SIM: ${{matrix.simulators}}

.github/workflows/cmake-builds.yml

@@ -24,6 +24,14 @@ jobs:
       run: |
         sh -ex .travis/deps.sh linux
         sudo apt install -ym ninja-build
+
+    - name: libslirp module
+      run: |
+        git submodule sync
+        git submodule set-url -- libslirp https://gitlab.freedesktop.org/bscottmichel/libslirp-minimal.git
+        git submodule set-branch --branch incr-minimal libslirp
+        git submodule update --init --recursive --remote
+
     - name: cmake-builder.sh
       run: |
         cmake/cmake-builder.sh --config Release --flavor ninja --lto --notest --parallel --verbose --cpack_suffix x86_64-${{matrix.os}}
@@ -47,7 +55,7 @@ jobs:
 
 
   cmake-macOS:
-    name: macOS 12+
+    name: macOS
     runs-on: ${{ matrix.os }}
     strategy:
       #-
@@ -57,32 +65,35 @@ jobs:
       # that the build produces.
       #
       # (*) "artefact" for the rest of the Anglosphere -
+      #
+      # As of 18 NOV 2024, Github deprecated macos-12.
       matrix:
-        os: [macos-12, macos-13, macos-14]
+        os: [macos-13, macos-14]
 
     env:
       CPACK_SUFFIX: ${{matrix.os != 'macos-14' && 'x86_64' || 'm1'}}.${{matrix.os}}
 
     steps:
     - uses: actions/checkout@v4
 
-    ## Workaround for remnant symlinks in /usr/local pointing back to
-    ## macOS frameworks.
-    ##
-    ## Future: Will have to keep an eye on SDL_ttf's Python dependency
-    ## so that the correct/appropriate Python version is removed.
-    - name: Remnant symlink cleanup
-      run: |
-        brew unlink python@3 || true
-        brew uninstall --ignore-dependencies python@3 || true
-        brew unlink [email protected] || true
-        brew uninstall --ignore-dependencies [email protected] || true
-        for f in $(find /usr/local/bin -type l -print); do \
-          (readlink $f | grep -q -s "/Library") && echo Removing "$f" && rm -f "$f"; \
-        done || exit 0
+    ## Nuke homebrew and start with a clean instance.
+    - name: Reinstall HomeBrew (macOS)
+      run: |
+        /usr/bin/sudo /bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/uninstall.sh)"
+        [ -d /opt/homebrew ] && ( sudo rm -rf /opt/homebrew/* || true )
+        [ -d /usr/local ]    && ( sudo rm -rf /usr/local/*    || true )
+        /bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install.sh)"
 
     - name: Install dependencies
-      run: sh -ex .travis/deps.sh osx
+      run: |
+        sh -ex .travis/deps.sh osx
+
+    - name: libslirp module
+      run: |
+        git submodule sync
+        git submodule set-url -- libslirp https://gitlab.freedesktop.org/bscottmichel/libslirp-minimal.git
+        git submodule set-branch --branch incr-minimal libslirp
+        git submodule update --init --recursive --remote
 
     - name: cmake-builder.sh
       run: |
@@ -123,6 +134,12 @@ jobs:
     runs-on: windows-latest
     steps:
     - uses: actions/checkout@v4
+    - name: libslirp module
+      run: |
+        git submodule sync
+        git submodule set-url -- libslirp https://gitlab.freedesktop.org/bscottmichel/libslirp-minimal.git
+        git submodule set-branch --branch incr-minimal libslirp
+        git submodule update --init --recursive --remote
     - name: Install v141_xp (XP toolkit) and build SIMH
       shell: pwsh
       run: |
@@ -189,8 +206,25 @@ jobs:
   cmake-vs2022:
     name: VS 2022 Win10 native VCPKG
     runs-on: windows-latest
+    strategy:
+      #-
+      # The CMake builds produce artifacts (*) and the runner image's name is
+      # used in the artifact's name, simh-4.1.0-x86_64-ubuntu-20.04.deb.
+      # Consequently, each runner image is enumerated for each artifact (*)
+      # that the build produces.
+      #
+      # (*) "artefact" for the rest of the Anglosphere
+      #-
+      matrix:
+        build: [vs2022, vs2022-x64]
     steps:
     - uses: actions/checkout@v4
+    - name: libslirp module
+      run: |
+        git submodule sync
+        git submodule set-url -- libslirp https://gitlab.freedesktop.org/bscottmichel/libslirp-minimal.git
+        git submodule set-branch --branch incr-minimal libslirp
+        git submodule update --init --recursive --remote
     - name: vs2022 build
       shell: pwsh
       run: |
@@ -206,34 +240,36 @@ jobs:
           Push-Location $env:VCPKG_ROOT
           git pull
           Pop-Location
-          ./cmake/cmake-builder.ps1 -flavor vs2022 -config Release -clean -lto -verbose -notest -cpack_suffix win32-native
+          ./cmake/cmake-builder.ps1 -flavor ${{matrix.build}} -config Release -clean -lto -verbose `
+                -notest `
+                -cpack_suffix ${{matrix.build}}
     - name: SIMH simulator suite test
       shell: pwsh
       run: |
-          ./cmake/cmake-builder.ps1 -flavor vs2022 -config Release -testOnly
+          ./cmake/cmake-builder.ps1 -flavor ${{matrix.build}} -config Release -testOnly
     ## Install isn't strictly necessary, but it's a good way to see what dependencies
     ## (IMPORTED_RUNTIME_ARTIFACTS) get installed.
     - name: Install
       shell: pwsh
       run: |
-        cmake/cmake-builder.ps1 -config Release -flavor vs2022 -installOnly
+        cmake/cmake-builder.ps1 -config Release -flavor ${{matrix.build}} -installOnly
     - name: SIMH packaging
       shell: pwsh
       run: |
-          cd cmake\build-vs2022
+          cd cmake\build-${{matrix.build}}
           cpack -G "NSIS;WIX;ZIP" -C Release
     - name: Upload ZIP
       uses: actions/upload-artifact@v4
       with:
-        name: simh-4.1.0-win32-vs2022.zip
-        path: cmake/build-vs2022/simh-4.1.0-win32-native.zip
+        name: simh-4.1.0-${{matrix.build}}.zip
+        path: cmake/build-${{matrix.build}}/simh-4.1.0-${{matrix.build}}.zip
     - name: Upload EXE installer
       uses: actions/upload-artifact@v4
       with:
-        name: simh-4.1.0-win32-vs2022.exe
-        path: cmake/build-vs2022/simh-4.1.0-win32-native.exe
+        name: simh-4.1.0-${{matrix.build}}.exe
+        path: cmake/build-${{matrix.build}}/simh-4.1.0-${{matrix.build}}.exe
     - name: Upload MSI installer
       uses: actions/upload-artifact@v4
       with:
-        name: simh-4.1.0-win32-vs2022.msi
-        path: cmake/build-vs2022/simh-4.1.0-win32-native.msi
+        name: simh-4.1.0-${{matrix.build}}.msi
+        path: cmake/build-${{matrix.build}}/simh-4.1.0-${{matrix.build}}.msi

.gitmodules

@@ -0,0 +1,4 @@
+[submodule "libslirp"]
+	path = libslirp
+	url = https://ourdoodlehouse.org/gitlab/scott/libslirp-minimal.git
+	branch = incr-minimal

.travis/deps.sh

@@ -30,6 +30,19 @@ install_linux() {
     sudo apt-get install -ym cmake cmake-data
 }
 
+install_mingw32() {
+    ## Doesn't have libpcap or cmake's extra modules. Not that this
+    ## makes much of a difference.
+    pacman -S --needed mingw-w64-i686-ninja \
+	mingw-w64-i686-cmake \
+        mingw-w64-i686-gcc \
+	mingw-w64-i686-make \
+        mingw-w64-i686-pcre \
+	mingw-w64-i686-freetype \
+        mingw-w64-i686-SDL2 \
+	mingw-w64-i686-SDL2_ttf
+}
+
 install_mingw64() {
     pacman -S --needed mingw-w64-x86_64-ninja \
 	mingw-w64-x86_64-cmake \
@@ -71,7 +84,7 @@ install_clang64() {
 
 
 case "$1" in
-  osx|macports|linux|mingw64|ucrt64|clang64)
+  osx|macports|linux|mingw32|mingw64|ucrt64|clang64)
     install_"$1"
     ;;
   arch-linux)